A circuit breaker is described, for example, by U.S. Pat. No. 4,810,840 which discloses, in FIG. 4, a switch with a movable contact that is driven by means of a drive rod. In this case, the contact has a cylindrical design and is guided through an opening in a metallic member. The member bears the quenching nozzle and the compression device. Under normal circumstances, it is very difficult to seal the opening from the hot quenching gases which occur during switching operations. Thus, hot quenching gases may penetrate into the space in which the drive rod moves. This creates the risk that the insulating support will be contaminated on its outside by quenching gases. When this occurs, electrically conductive films may settle on the insulating member which could adversely affect its insulating properties and thus lead to inadvertent discharging.
Therefore, it would be advantageous to provide a design that protects the drive rod and the insulating support from the effect of switching gases.